correct offset localtime for comments ago

isso/js/app/globals.js

@@ -10,7 +10,7 @@ define(function() {
     };
 
     Offset.prototype.localTime = function() {
-        return new Date((new Date()).getTime() + this.values.reduce(
+        return new Date((new Date()).getTime() - this.values.reduce(
             function(a, b) { return a + b; }) / this.values.length);
     };
 
@@ -18,4 +18,4 @@ define(function() {
         offset: new Offset()
     };
 
-});
+});